Bremsstrahlung Cross Section with Polarized Beams for Luminosity Determination at the EIC

TL;DR

This paper calculates the polarized bremsstrahlung cross section at leading order for electrons and ions, providing analytic expressions crucial for luminosity measurements at the upcoming EIC, highlighting the suppression of polarization-dependent components.

Contribution

It derives analytic expressions for polarized bremsstrahlung cross sections at leading order, essential for EIC luminosity calibration, and analyzes polarization effects relative to unpolarized components.

Findings

Polarization-dependent cross section component is highly suppressed.

Analytic expressions are provided for differential cross sections.

Polarization effects are minimal due to low $q^2$ in bremsstrahlung.

Abstract

The bremsstrahlung cross section is calculated at leading order for polarized beams of electrons and ions, which is needed for luminosity measurements at the upcoming Electron Ion Collider (EIC). Analytic expressions, differential in the emitted photon energy and polar angle, are derived. The component of the cross section which depends on the beam polarizations is found to be highly suppressed with respect to the unpolarized Bethe-Heitler component, owing to the low $q^2$ that characterizes the bremsstrahlung process.